Embodiments relate to cementing operations and, in certain embodiments, to methods and systems for the transportation and delivery of set-delayed cement compositions to a well site.
Cement compositions may be used in a variety of subterranean operations. For example, in subterranean well construction, a pipe string (e.g., casing, liners, expandable tubulars, etc.) may be run into a wellbore and cemented in place. The process of cementing the pipe string in place is commonly referred to as “primary cementing.” In a typical primary cementing method, a cement composition may be pumped into an annulus between the walls of the wellbore and the exterior surface of the pipe string disposed therein. The cement composition may set in the annular space, thereby forming an annular sheath of hardened, substantially impermeable cement (i.e., a cement sheath) that may support and position the pipe string in the wellbore and may bond the exterior surface of the pipe string to the subterranean formation. Among other things, the cement sheath surrounding the pipe string may function to prevent the migration of fluids in the annulus and protect the pipe string from corrosion. Cement compositions may also be used in remedial cementing methods, for example, to seal cracks or holes in pipe strings or cement sheaths, to seal highly permeable formation zones or fractures, to place a cement plug, and the like. Cement compositions may also be used for the placement of a cement plug in plug-and-abandon operations.
A broad variety of cement compositions have been used in subterranean cementing operations. In some instances, set-delayed cement compositions have been used. Set-delayed cement compositions have an extended set in that they are specially formulated to remain in a pumpable fluid state for about one day or longer (e.g., about 7 days, about 2 weeks, about 2 years, or longer) at room temperature (e.g., about 80° F.) in storage. When desired for use, the set-delayed cement compositions should be capable of being activated whereby reasonable compressive strengths are developed. For example, a cement set accelerator may be added to a set-delayed cement composition whereby the composition sets into a hardened mass. Among other things, the set-delayed cement composition may be suitable for use in wellbore applications, for example, where it is desired to prepare the cement composition in advance. This may allow, for example, the cement composition to be stored prior to its use. In addition, this may allow, for example, the cement composition to be prepared at a convenient location and then transported to the job site. While set-delayed cement compositions have been developed heretofore, challenges exist with their successful use in subterranean cementing operations. For example, the successful preparation, storage, and transportation of the set-delayed cement composition may be problematic. Specifically, the set-delayed cement compositions typically contain significant quantities of solids that can settle or otherwise segregate in the mix water when stored for extended periods of time. This can prevent being able to use conventional pumping systems to circulate the material and/or remove it from storage containers in order to pump it downhole. Additionally, settling and/or segregation may also undesirably result in a non-homogenous composition, which can cause premature setting, late setting, and/or lack of setting of the composition.